Post Bridge, Upload-Post, Late, Mixpost and Bundle.social: five posting APIs compared

Post Bridge starts at $29 a month for 5 accounts with MCP included; REST access adds $5. Upload-Post offers a free API plan. Late is now Zernio. Mixpost is self-hosted, while Bundle.social sells hosted plans with post allowances. Here is how their prices, account units and agent integrations compare, checked September 14, 2026.

The table

Prices in USD, checked September 14, 2026, with PlugKit as a reference. Annual commitments and one-time licences are labelled separately; MCP access is not the same as REST access.

Upload-Post counts profiles, each connecting one account per platform: five profiles can hold five Instagram accounts plus five YouTube accounts. Bundle.social limits posts, Zernio charges graduated account fees, and Mixpost leaves hosting and maintenance to you.

Post Bridge: MCP included, the REST API costs $5 more

Post Bridge's pricing page lists Starter at $29/month for 5 connected accounts, Creator at $39 for 15, Growth at $59 for 50 and Pro at $99 for unlimited accounts. Posts are unlimited on all four. There is a 7-day trial rather than a permanent free plan.

The distinction for developers is REST versus MCP. The API overview prices REST access as a $5/month add-on. The agent page explicitly lists Starter at $29 with MCP already included, and $34 with REST and skills access. An agent using the included MCP does not automatically need the REST add-on.

Documented agent workflows cover publishing, scheduling, media uploads and analytics. A skill (npx skills add post-bridge-hq/agent-mode) and CLI are also available. Check client compatibility and supported destinations; publishing support does not establish inbox access.

Upload-Post: 22 destinations, a free plan with API and MCP

Upload-Post publishes both a month-to-month and an annual rate for each paid plan. From its own pricing reference on the review date:

The developer documentation advertises 10 free uploads/month. Basic is $24 monthly or $192 paid annually, equivalent to $16/month. The pricing reference excludes TikTok from Free; check eligibility for each destination. An optional X link-posting add-on costs $19/month, billed monthly even with an annual plan, for up to 50 link posts.

Its 22 destinations mix social networks with messaging and developer publishing services, including Dev.to, Hashnode, Lemmy and Nostr. Check the supported features and plan restrictions for each destination.

The REST API uses https://api.upload-post.com and an Authorization: Apikey YOUR_API_KEY header. The MCP documentation explicitly includes the free plan, authenticated with an API key. Its hosted endpoint is https://mcp.upload-post.com/mcp; a local option also exists. Tools cover publishing, comments, DMs and automations, subject to platform permissions and plan limits, not identical engagement support across every destination.

Late is now Zernio: same API, new name

Late has rebranded to Zernio. Its rebrand page preserves API routes, schemas, keys and OAuth tokens; renaming environment variables is optional. Old and new SDK packages receive parallel maintenance for six months, followed by a deprecation notice for the old names, not a shutdown. The old packages continue to work.

Account pricing is graduated: the first 2 have no account fee, accounts 3 to 10 cost $6 each per month, 11 to 100 cost $3 each and those above 100 cost $1 each. Ten accounts therefore cost $48/month and 100 cost $318/month in account fees. Separate charges, including X operations, can apply even when the account fee is zero.

One upcoming change needs a date: outbound-message billing starts on October 1, 2026. The first 10k qualifying outbound messages per team per month are included, then the rate is $1 per additional 10k messages. Before October 1, that meter is tracked but not charged. Incoming messages, comment replies and reads are excluded from this meter; X DMs and SMS follow separate billing.

Against PlugKit Pro's $97/month for 30 accounts, Zernio's account fee is $96 at 26 accounts, $99 at 27 and $108 at 30. That is an account-fee comparison, not a claim that the features or total usage bills are equivalent. The broader comparison is in the Zernio alternative page.

Mixpost: a one-time licence, on your own server

Mixpost is the self-hosted option. Lite is free and lists Facebook Pages, X and Mastodon. Pro costs $299 once for one domain, with unlimited accounts, API access, analytics, an AI assistant and approval workflows. It includes a year of updates; the purchased version can continue to run afterward. Enterprise is $1,199 once and adds features including subscription management and white-label branding.

Mixpost is not REST-only. Its native MCP integration runs on your own instance and exposes tasks including drafting, scheduling and publishing. Check the edition and permissions rather than assuming every Lite installation has the same integration surface as Pro.

The $299 licence costs less than eleven $29 payments ($319), but excludes hosting, maintenance, update renewals and provider setup. Self-hosting controls the application infrastructure, not the social platforms or optional AI services receiving content.

Choose it when that control is worth operating the service yourself. For another self-hosting option with a separately offered hosted service, see the Postiz alternative page.

Bundle.social: unlimited accounts, priced by posts

Bundle.social's pricing starts at $0 for 3 social accounts and 20 posts/month, with the API included. Pro is $100/month for unlimited accounts and 10k posts; Business is $400 for 100k posts. Enterprise pricing is custom. These are subscription tiers with post allowances, not a single automatic per-post overage rate.

X posts have a separate prepaid charge: $0.015 for a standard post or $0.20 for a post containing a link. Those charges are additional to the subscription. The same distinction must be included when comparing with PlugKit, rather than displaying only its lower standard-post rate.

Bundle.social also documents a local MCP server, with publishing, analytics and comment-management tools. The remote hosted MCP server is on its roadmap, not a released feature in the documentation reviewed here. Local MCP is still an agent integration; it is not equivalent to having REST only.

Unlimited accounts can suit products connecting many customers. Compare post volume, X activity and required features before concluding that it is cheaper.

Which one an AI agent can actually drive

Compare hosting, authentication and platform permissions. These are documented examples, not product-tested capabilities or exhaustive lists of missing features.

PlugKit's billing documentation lists Creator at $29/month for 5 accounts and Pro at $97 for 30. Pro's extra accounts cost $3 each for accounts 31 to 100 and $1.50 each above 100. Its hosted MCP endpoint is https://api.plugkit.co/mcp. The messaging guide distinguishes inbox support by channel, and the Threads guide documents Threads publishing. A single API does not promise identical capabilities on every platform.

X is additional: $0.005 for a post read, $0.010 for several other reads, $0.015 for a standard post or $0.20 for a post containing a URL. For example, 100 URL-containing posts represent $20 in X posting charges, not $1.50, before the subscription or other operations. Compare that workload consistently against competitors' rates or add-ons.

The setup is in the Hermes Agent guide, and the wider landscape is in the social media API guide.

$29 a month for 5 connected accounts, cancel anytime.

FAQ

Is Post Bridge worth it compared to the alternatives?

Starter offers 5 accounts and MCP for $29/month; REST and skills access bring it to $34. Pro offers unlimited accounts at $99/month. Compare those allowances with your workflow, not a claim that it is universally the cheapest: the other options include free plans, different billing units and annual commitments.

What happened to Late, the social media API?

Late became Zernio. Its rebrand documentation says the existing API, keys and OAuth tokens remain compatible. Package and environment variable names can be updated, but the six-month SDK transition is not a requirement to rename variables before the service stops working.

Which of these has a free plan?

Upload-Post documents 10 uploads/month and 2 profiles with API and MCP access. Bundle.social includes API access with 20 posts/month and 3 accounts. Mixpost Lite has no licence fee but requires hosting; Zernio's first two accounts have no account fee. Platform restrictions and separate usage charges can still apply.

Is Mixpost cheaper than a hosted API?

Its $299 Pro licence costs less than eleven $29 monthly payments. That calculation excludes hosting, maintenance, future updates and provider setup. It can be economical for some workloads, but the licence price alone does not establish the total cost or feature equivalence.

Can I connect these to Claude or another AI agent?

All five document an MCP integration, but deployment differs: Post Bridge, Upload-Post and Zernio have hosted servers, Mixpost runs on your instance, and Bundle.social provides a local server. PlugKit also has a hosted endpoint. Confirm client compatibility, credentials and task permissions; see social media MCP servers compared for the broader overview.

AB

Antoine BlancoFounder of PlugKit. Runs his own Instagram, YouTube and X accounts through the API and MCP server described here.